#include<stdio.h>
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};
struct TreeNode* invertTree(struct TreeNode* root) {
    if (root == NULL) {
        return NULL;
    }
    struct TreeNode* tmp = root->left;
    root->left = root->right;
    root->right = tmp;
    invertTree(root->left);
    invertTree(root->right);
    return root;
}
int main()
{
	return 0;
}